The present invention relates generally to aircraft aerodynamics and specifically to a method and apparatus for attenuating the lift-induced vortex generated by the wings of an aircraft.
The lift-induced vortex system associated with large jet aircraft has become a major problem to the air traffic controller as an unseen hazard to smaller following aircraft. The problem arises from the fact that the vortex system created by large aircraft is very strong and of such long persistence and that it intensifies as the weight of the aircraft increases. The rotational airflow or vortex developed at or near the wingtip of an aircraft remains essentially stationary in space and induces a rolling moment on smaller following aircraft is encountered. This rolling moment can be so strong that it surpasses the limits of control of the smaller aircraft and such loss of control has been proven to occur as far as 4 miles behind a large aircraft. The vortex problem is particularly severe in flight paths around major airports where smaller aircraft are most likely to follow large aircraft and during landing where the small aircraft has little altitude in which to regain control.
The vortex system also causes the induced drag of the aircraft which, for transport-type aircraft, is 35 to 40% of the total drag of the aircraft. Aircraft wings are designed to shed the vortex system along the span of the wing to reduce the concentrated vortex centered just behind each wingtip. The final roll-up of the vortex system is further behind the wing thereby reducing, but not eliminating, its ill effect on the drag of the aircraft.
Previous attempts to limit the vortex effect have generally been unsuccessful either because, as with wing end plates or wingtip extensions, the devices did not sufficiently modify the far downstream effects of the vortex or, as with landing flap variations and wing spoilers, the vortex attenuation caused too great a lift loss for the aircraft. These devices are only concerned with attenuating wingtip vortices, not with attenuating the entire vortex system.
It is an object of the present invention to attenuate the total vortex system produced by an aircraft.
It is another object of this invention to provide an apparatus which is effective on all types of aircraft.
It is a further object of this invention to provide an apparatus which causes an increase in wing lift rather than a reduction when deployed.
It is yet another object of the present invention to accomplish the foregoing objects in a simple manner.
Additional objects and advantages of the present invention are apparent from the drawings and specification which follow.